Euphemism for police interrogation. When invited to “tea,” one is asked about their political activities and warned against further involvement. Those compelled to attend these tea sessions is said to have been “tea-drinked.”

火光微语: @郭玉閃又日 Brother Murong Xuecun “surrendered” himself to the police. Today, he was summoned to the Purple Bamboo Park police station for questioning at five in the afternoon. He's still drinking tea with the police, and I'm waiting for him at a bar outside the station.